Polycarbonates, poly(ester carbonates), and polyarylates are well known thermoplastic materials which due to their many advantageous physical properties, find use as thermoplastic engineering materials in many commercial and industrial applications. These resins, for example, exhibit excellent properties of toughnes, flexibility, impact strength, and heat resistance. All such resins may generally be prepared by the reaction of a dihydric phenol, such as bisphenol-A, with a carbonate precursor and/or an aromatic dicarboxylic acid or a reactive derivative thereof.
These resins, have been commonly blended with other resins to produce blends having various modified properties. For example, blends of these resins with a second and even third thermoplastic resin can lead to blends which not only have the above mentioned properties but additionally have excellent properties for which polycarbonate, poly(ester carbonate), and polyarylate may not otherwise be recognized, such as chemical resistance, hydrolytic stability, resistance to brittle failure, processability and gas barrier properties.
For some important applications, i.e., automotive parts, it is important that such resins have enhanced chemical resistance to aggressive solvents, for example acetone, aromatic solvents, gasoline, and the like, to a degree which may not be necessary in most other applications. In the above mentioned application Ser. No. 812,433 it is disclosed that the necessary levels of solvent resistance in combination with excellent levels of other necessary properties are achieved by use of certain novel blends of polycarbonate, poly(ester carbonate), or polyarylate with polyamide. There is, however, in some cases a tendency for the molded articles to delaminate, possibly due to a lack of compatibility between the resin phases.
In the above mentioned application Ser. No. 117,250 block copolymers comprising polyamide segments and polyarylate segments are disclosed to be useful per se as molding resins, as packaging materials and as blending resins with other thermoplastics.
Such polyamide-polyarylate block copolymers now, surprisingly, have been found to significantly improve the compatibility of blends of polyamides with polycarbonates, poly(ester carbonates) or polyarylates. Molded articles containing an effective amount of the polyamide-polyarylate block copolymer have much less tendency to delaminate and they exhibit high notched Izod impact values, especially in rubber modified versions. The block copolymers for use in this invention can be prepared either from the monomers, or from terminally-reactive polymers, respectively.
The present invention, therefore, produces blends containing polyamides and polycarbonate, poly(ester carbonate), or polyarylate which otherwise exhibit the desirable properties of such resins including in some cases, transparency, but which also exhibit excellent solvent resistance, ductility, and resistance to brittle failure without evidence of incompatibility.